doc: modular sandbox configs

docs/add-sandbox.md

@@ -47,7 +47,7 @@ docker build --file images/python/Dockerfile --tag codapi/python:latest images/p
 
 And register the image as a Codapi _box_ in `configs/boxes.json`:
 
-```json
+```js
 {
     // ...
     "python": {
@@ -56,12 +56,10 @@ And register the image as a Codapi _box_ in `configs/boxes.json`:
 }
 ```
 
-Finally, let's configure what happens when the client executes the `run` command in the `python` sandbox. To do this, we edit `configs/commands.json`:
+Finally, let's configure what happens when the client executes the `run` command in the `python` sandbox. To do this, we create `configs/commands/python.json`:
 
-```json
+```js
 {
-    // ...
-    "python": {
     "run": {
         "engine": "docker",
         "entry": "main.py",
@@ -73,19 +71,16 @@ Finally, let's configure what happens when the client executes the `run` command
         ]
     }
 }
-}
 ```
 
 This is essentially what it says:
 
 > When the client executes the `run` command in the `python` sandbox, save their code to the `main.py` file, then run it in the `python` box (Docker container) using the `python main.py` shell command.
 
-What if we want to add another command (say, `test`) to the same sandbox? Let's edit `configs/commands.json` again:
+What if we want to add another command (say, `test`) to the same sandbox? Let's edit `configs/commands/python.json` again:
 
-```json
+```js
 {
-    // ...
-    "python": {
     "run": {
         // ...
     },
@@ -101,7 +96,6 @@ What if we want to add another command (say, `test`) to the same sandbox? Let's
         ]
     }
 }
-}
 ```
 
 Besides configuring a different shell command, here we increased the maximum output size to 8Kb, as tests tend to be quite chatty (you can see the default value in `configs/config.json`).